Control for welding generators



Nov. 1, 1938. J. H. BLANKENBUEHLER ET AL. 4

CONTROL FOR WELDING I GENERATORS Filed May 4, 1954 INVENTORS .Jc'ihn/l E/an Aen bu: h/er and [fr/he I Fees,

' ATTOR Y WITNESSES:

Patented Nov. 1, 1938 2,135,045

UNITED STATES PATENT OFFICE CONTROL FOR WELDING GENERATORS John H. Blankenbuehler, Edgewood, and Irvine J. Rees, Turtle Creek, Pa., assignors to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsylvania Application May 4, 1934, Serial No. 723,878

' 12 Claims. (Cl. 171-'-118) Our invention relates, generally, to electrical operated to open the contact members after the control systems and it has particular relation to expiration of a predetermined time interval. The control systems for motor-generator arc welding operating winding of the main switch is theresets. upon deenergized and the set is disconnected The object of our invention, generally stated, from the power source. 5 is to provide a control system for motor-gen- In the event that current is caused to flow in erator arc welding sets which shall be simple the welding circuit before the expiration of the and eflicient in operation and which may be predetermined interval of time, the time delay readily and economically manufactured and indevice will automatically reset.

stalled. The opening of the main switch is accompanied to The principal object of our invention is to proby the opening of the welding circuit. This cirvide for disconnecting the driving motorof a cuit is opened in order to permit the main switch motor-generator set, disposed to supply current to be closed by the engagement of the welding to a Welding circuit, from a power source, a preelectrode with the work.

determined interval of time after welding cur- Referring now particularly to the single figure l5 rent ceases to flow. of the drawing, the reference character I desig- Another important object of our invention is to nates generally a three-phase squirrel-cage alprovide for connecting the driving motor of a ternating current motor which is arranged to motor-generator set, disposed to supply current drive a welding generator, shown generally at 2.

to a welding circuit, to a power circuit in re- The welding generator 2 comprises an armature 20 sponse to the establishment of the welding cir- 3 and a differential series field winding 4 which cuit. are connected through a resistor 5 to supply cur- A further object of our invention is to provide rent to a welding circuit comprising the confor automatically resetting a time delay device, ductors 6 and i. As illustrated, the conductors which is initiated into operation on cessation of 6 and l are connected, respectively, to the weld- 2g flow of welding current, provided that the welding electrode 8 and work 9 between which a ing current is caused to flow within the predeterwelding arc I0 is maintained for performing the mined time interval for which the device is set. welding operation. An exciter generator, shown Other objects of our invention will in part be generally at I2, is provided for energizing a main obvious and in part appear hereinafter. field winding l3 located on the generator 2. An 30 Our invention accordingly is disclosed in the adjustable resistor I4 is provided in series circuit embodiment thereof shown in the accompanyrelation with the main field winding I3 for reguing drawing and comprises the features of conlating the flow of current therethrough to adjust struction, combination of elements, and arrangethe output of the generator 2 to thedesired value.

ment of parts which will be exemplified in the The motor I may be connected to a suitable 35 construction hereinafter set forth and the scope source of three-phase current which may be indiof the application of which will be indicated in cated by the energized conductors l5, l6 and H. the appended claims. A motor main switch, shown generally at l8iand For a more complete understanding of the having operating winding I 9,is provided for connature and scope of our invention, reference may heating the motor I at contact members [8a, Mb 40 be had to the following detailed description taken and. I80 to the conductors l5, l6 and I1, respecin connection with the accompanying drawing, tively. It will be understood that other types of in which the single figure diagrammatically motors may be used instead of the motor I illusrepresents a control system organized in actrated and described herein and also that other cordance with our invention. types of welding generators 2 may be employed. 45

In Order to provide at ca y discon- The motor generator set illustrated and described e t t e motor of a motor generator arc weldherein is used for illustrative purposes only. ing s t f the power Source. Contact members At the same time that the motor main switch are utilized which are connected in series circuit [a is i d, a n rator main switch, shown relation with the operating winding of the main generally t 20 having an operating winding 2i, 50

Switch which used to Connect the motor to is also energized to connect at contact members the power source. A current responsive relay 20a the generator 2 to the welding circuit comis provided for initiating the operation of a time prising the conductors 6 and 1. The generator delay device so that, on cessation of current flow main switch 20 is provided in order to disconnect 5 in the welding circuit, the time delay device is the welding circuit from the generator 2 in order to permit a desired control function which will 'be set forth hereinafter and which would not be possible if the generator 2 were not disconnected from the welding circuit. While a separate operating winding 2| is shown for operating the generator main switch 28, it will be understood that all of the contact members operated thereby may be also operat d by the motor main switch I8 if desired. However, in order to more clearly illustrate the invention the switches I8 and I9 are shown separately but with their operating windings I9 and 2| connected in parallel circuit relation so that the switches I8 and 20 will be operated simultaneously.

In order to eiiect the deenergization of the operating winding I9 of the motor main switch at the expiration of a predetermined time interval after current ceases to flow in the welding circuit, a time delay device, shown generally at 25, is provided. It comprises a motor, shown generally at 26, having a field structure 21 and a field winding 28. A rotor 29 is rotatably and slidably mounted between the pole pieces of the field structure in a manner such that when the field winding 28 is deenergized, the rotor 29 is dropped out of alignment with the field structure 21 to the position illustrated in the drawing. On energization of the field winding 28, the rotor 29 not only is caused to revolve but is also caused to move upwardly to assume a position of minimum reluctance.

Advantage is taken of the movement of the rotor 29 to cause a pinion 3| driven thereby to en gage a gear wheel 32 forming a part of a gear train, shown generally at 34. The gear train 34 is mounted, as illustrated, between brackets 35 and 36 which may be secured to the field structure 21. An operating arm 31 is secured to the last gear Wheel 38 of the gear train 34 and is rotatable therewith. A spring 39, secured to the o erating arm 31 and the upper bracket 35, is provided for retrieving the operating arm 31 when the winding 28 is deenergized and the pinion 3| is moved out of engagement with gear wheel 32.

As shown in the drawing, the operating arm 31 is arranged to engage a bridging contact member 42 which is pivotally mounted on an extension of the lower bracket 36. The bridging member 42 is biased by means of a spring 43 into engagement with contact members 44 so tha they are normally closed thereby.

When the field winding28 is energized, the rotor 29 is moved upwardly and rotated as set forth hereinbefore to cause the pinion 8| to engage and rotate the gear wheel 32 and the remaining gears of the gear train 34. The operating arm 31 is moved until it engages the bridging contact member 42 and moves it out of engagement with the contact members 44. The bridging contact member 42 is so arranged that it will cause the motor 29 to stall so long as the field winding 28 remains energized. The motor 28 is so constructed that such operation thereof is permissible due to the relatively high impedance of the field winding 28, which is not appreciably altered when the rotor 29 is permitted to revolve.

The operation of the time delay device 25 is controlled by means of a current-responsive relay, shown generally at 48, having an operating winding 49 connected in shunt circuit relation with the resistor 5 in the welding circuit. It will be understood that the operating winding 49 may be inserted directly in the circuit to the generator 2 if it is desired to conduct the total weldin current through it.

In the event that is desired to manually control the operation of the motor I8, start and stop push buttons 5! and 52, respectively, are pro vided. The former is arranged to directly connect the operating winding I9 of the motor main switch I8 and the operating winding 2| 0! the generator main switch 20 to the energized con ductors I8 and I! while the latter is arranged to open the energizing circuit thereto.

In operation, it will be assumed that the conductors I5, I6 and ii are energized, that the welding operation is not being performed and that the motor main switch I8 is in the position shown in the drawing. Under these conditions, the generator main switch 28 will also be in the position shown in the drawing, the operating winding 49 of relay 48 will be deenergized and the time delay device 25 will also be in the posltion illustrated in the drawing. In order to initiate the operation of the motor I, the operator contacts the welding electrode 8 with the work I to complete a circuit for energizing the operating windings I9 and 2| of the switches I8 and 28, respectively.

The circuit for energizing operating windings I9 and 2| may be traced from the energized conductor II through conductor 55, operating windings I9 and 2| in parallel, conductor 58, contact members I 811 of the switch I8 which are closed, conductors 51 and 8, the welding electrode 8 and work 9, conductors I and 58, contact members 44 which are closed and conductor 59 to the energized conductor I8.

As soon as the main switch I8 is closed, contact members I8d are opened to disconnect the energizing circuit of the operating windings I9 and 2| from the welding circuit. The energizing circuit for these windings, however, is completed by the closure of contact members 201) on the switch 28 so that the energizing circuit for the operating windings I9 and 2| will be maintained closed. It will be understood that the contact members 2817 may be adjusted to be bridged just prior to the time when the contact members I8d are opened.

The closure of the generator main switch 28 also closes contact members 280 and the field winding 28 of the motor 28 is energized. As soon as welding current starts to flow, however, the operating winding 49 of the current responsive relay 48 is energized to open at contact members 48a the circuit for energizing the winding 2:.

As a result the operating arm 31 is retrieved by the spring 39 to its initial position.

The circuit for energizing the field winding 28 may be traced from the energized conductor I! through conductor 6 field winding .28, conductor 62, contact members 280, conductor 88, contact members 48a and conductor 84 to the energized conductor I8.

When welding current ceases to flow in the welding circuit, as for instance when the welding operation is terminated, the operating winding 49 of the current responsive relay 48 is no longer energized and contact members 480. are bridged. The winding 28 of the motor 26 is then energized over the circuit hereinbefore described and the rotor 29 is caused to move u wardly and -revolve so that the pinion 3| will engage and rotate the gear wheel 32. If the welding circuit is not reestablished within the time for which the time delay device 25 is adjusted, the operating arm 31 will engage the bridging member 42 and will remove it from engagement with the contact members 44 to open the energizing circuit to the operating windings I8 and 2| oi! the main switches I 8 and 20, which will thereupon be opened. The motor I will then be disconnected from the power source and will stop. At the same time, the welding circuit will be disconnected from the welding generator 2, the field winding 28 will be deenergized and the time delay device 25 will be reset to the initial position.

It will be observed that it is desirable to disconnect the welding circuit from the welding generator 2 in order to permit the operator to initiate the closure of the main switches I8 and 20 by contacting the welding electrode 8 with the work 9. If the circuit to the generator 2 were not opened, the armature 3 and series field winding 4 would cause a short circuit across the welding circuit which would render ineffective the contacting of the welding electrode 8 with the work to effect the desired control function.

When it is desired to again perform the welding operation, the operator may again contact the work 9 with the welding electrode 8 and theforegoing cycle of operations will then be repeated.

Since certain further changes may be made in the above construction and different embodiments of the invention may be made without departing from the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

We claim as our invention:

1. The combination with a motor having driving connection with a generator for supplying cur rent to a load circuit and means for opening and closing the load circuit, of control apparatus for automatically connecting and disconnecting the motor to and from a power source comprising switch means for connecting the motor to the power source and the generator to the load circurrent to a load circuit and means for opening and closing the load circuit, of control apparatus for automatically connecting and disconnecting the motor to and from a power source comprising switch means for connecting the motor to the power source and the generator to the load circuit, operating means for said switch means, normally closed contact means, circuit means for connecting said operating means to said power source through said normally closed contact means on closure of the load circuit thereby closing said switch means, and a control motor disposed to be connected for energization to the power source on opening of the load circuit for opening said normally closed contact means a predetermined interval of time after'opening of the load circuit.

3. The combination with a motor having drivsource through said normally closed contact 5 means on closure of the load circuit thereby closing said switch means, time delay means for opening said normally closed contact means a predetermined interval of time after energization thereof, and a relay connected to be responsive to the flow of current in the load circuit for initiating the operation of said time delay means on cessation of flow. of load current.

4. The combination with a motor having driving connection with a generator for supplying current to a load circuit and means for opening and closing the load circuit, of control apparatus for automatically connecting and disconnecting the motor to and from a power source comprising switch means for connecting the motor to the power source and the generator to the load circuit, operating means for said switch means, normally closed contact means, circuit means for connecting said operating means to said power source through said normally closed contact means on closure of the load circuit thereby closing said switch means, a control motor for opening said normally closed contact means a predetermined interval of time after energization thereof, and a relay connected to be responsive to the flow of current in the load circuit for effects ing the energization of said control motor on cessation of flow of load current.

5. The combination with a motor having driving connection with a generator for supplying current to a load circuit, of control apparatus for automatically disconnecting the motor from a power source comprising a main switch for connecting the motor to the power source, an operating winding for said main switch, normally closed contact means, circuit means for connecting said operating winding to the power source through said normally closed contact means immediately upon closure of the load circuit, and time delay means for effecting the opening of said normally closed contact means a predetermined interval of time after cessation of flow of load current.

6. The combination with a motor having driving connection with a generator for supplying current to a load circuit, of control apparatus for automatically disconnecting the motor from a power source comprising a main switch for connecting the motor to the power source, an operating winding for said main switch, normally closed contact means, circuit means for connecting said operating'winding to the power source through said normally closed contact means immediately upon completion ot the load circuit, a control motor for opening said normally closed contact means a predetermined interval of time after energization thereof, and a relay connected to be responsive to the flow of current in the load circuit for elfecting the energization of said control motor on cessation of flow of load current.

' '7. The combination with a motor having driving connection with a generator for supplying current to a load circuit and means for opening and closing the load circuit, of control apparatus for automatically connecting and disconnecting the motor to and from a power source comprising motor switch means for connecting the motor to the power source, generator switch means for connecting the generator to the load circuit. 0p-

erating means individual to each switch means, normally closed contact means, circuit means for connecting the operating means individual to said motor switch means to said power source through said normally closed contact means on closure of the load circuit, and time delay means for opening said normally closed contact means a predetermined interval of time after the load circuit is opened.

8. The combination with a motor having driving connection with a generator for supplying current to a load circuit and means for opening and closing the load circuit, of control apparatus for automatically connecting and disconnecting the motor to and from a power source comprising motor switch means for connecting the motor to the power source, generator switch means for connecting the generator to the load circuit, operating means individual to each switch means, normally closed contact means, circuit means for connecting the operating means individual to said motor switch means to said power source through said normally closed contact means on closure of the load circuit, and a control motor disposed to be connected for energization to said power source on opening of the load circuit for opening said normally closed contact means a predetermined interval of time after opening of the load circuit.

9. The combination'with a motor having driving connection with a generator for supplying current to a load circuit and means for opening and closing the load circuit, of control apparatus for automatically connecting and disconnecting the motor to and from a power source comprising motor switch means for connecting the motor to the power source, generator switch means for connecting the generator to the load circuit, operating means individual to each switch means, normally closed contact means, circuit means for connecting the operating means individual to said motor switch means to said power source through said normally closed contact means on closure of the load circuit, time delay means for opening said normally closed contact means a predetermined interval of time after the load circuit is opened, and relay means connected to be responsive to the flow of current in the load circuit for initiating the operation of said time delay means on cessation of flow of load current.

10. The combination with a motor having driving connection with a generator for supplying current to a load circuit and means for opening and closing the load circuit, of control apparatus for automatically connecting and disconnecting the motor to and from a power source comprising motor switch means for connecting the motor to the power source, generator switch means for connecting the generator to the load circuit, operating means individual to each switch means, normally closed contact means, circuit means for connecting the operating means individual to said motor switch means to said power source through said normally closed contact means on closure of the load circuit, a control motor for opening said normally closed contact means a predetermined interval of time after energization thereof, and a relay connected to be responsive to the flow of current in the load circuit for effecting the energization of said control motor on cessation of flow of load current.

11. A power supply system for changing electrical energy of one form to electrical energy of another form comprising a motor generator set, a primary source of electrical energy for driving the motor of said set, a switch for connecting and disconnecting the motor from said primary source, means for opening and closing the output circuit of the generator, means for automatically closing said switch responsive to the closure of the output circuit from the generator of said set, means responsive to the flow of current of a predetermined value from said generator for holding said switch closed, and means responsive to the cessation of the flow of current from said generator for a predetermined time for opening said switch.

12. The combination with a motor having driving connection with a generator for supplying current to a load circuit, of control apparatus for automatically connecting and disconnecting the motor to and from a power source comprising motor switch means for connecting the motor to the power source, generator switch means for connecting the generator to the load circuit, operating means individual to each switch means, normally closed contact means, circuit means for connecting the operating means individual to said motor switch means to said power source through said normally closed contact means on closure of the load circuit, and time delay means for opening said normally closed contact means a predetermined interval of time after the load circuit is opened.

JOHN H. BLANKENBUEHLER. IRVINE J. REES. 

